Actuator for dirigible wheels



Dec. 27, 1949 s. l. MacDUFF 2,492,649

ACTUATOR FOR DIRIGIBLE WHEELS Filed April 14, 1947 2 She'ets-Sheet l INVENTOR.

525MB Z Ma 5W M 3 W I .Dec. 27, 1949 s. 1. MacDUFF 7 2,492,649

ACTUATOR FOR DIRIGIBLE WHEELS Filed April 14, 1947 2 Sheets-Sheet 2 HVVENZUR,

dm/gz w Z Mic 505*" ATM/8N5) Patented Dec. 27, 1949 ACTUATOR FOR DIRIGIBLE W'I IEELS Stanley 1. MacDuif, South Bend, Ind., assignor to Bendix Aviation Corporation, SouthBend, Ind., a corporation of Delaware I 7 Application April 14, 1947, Serial No. 741,181

in the provision of an actuator carried by a Y 3 Claims. w(01144- 50) landing gear and remotely controlled for hydraulically steering a wheel mounted thereon.

It is a further object of the invention to provide an actuator including a hydraulic motor associated therewith so constituted that the load on the piston of the motor is carried by a bearing slidable with the piston.

It is an object of the invention to provide an actuator for steering the nose wheel of an aircraft, which actuator comprises two cylinders mounted with their axes at right angles and having a rack and sector therein for imparting motion to said wheel.

The above and other objects and features of the invention will be apparent from the following description of the apparatus taken in connection with the accompanying drawings which form a part of this specification, and in which:

Figure 1 is a view of the device of the invention mounted on a shock strut for guiding the nose wheel thereof;

Figure 2 is a view of the device of the invention with its associated hydraulic motor shown partly in longitudinal section;

Figure 3 is a transverse sectional view of the device taken on the lines 3-3 of Figure 2; and

Figure 4 is a view in isometric of the cylinders of the actuator before assembling.

Referring to Figure 1 of the drawings, reference numeral I designates a shock strut or landing gear of conventional design on which a wheel I2 is mounted for steering an aircraft, not shown. The wheel is mounted for rotation on an axle l4 integral with a tube [6 which telescopes into a larger tube H3. The inner tube [6 slides and rotates freely in the outer or larger tube I8 to permit pivoting about an axis normal to the wheel axle for steering. A collar 20 fits over one end of the outer tube l8 and bears at one end on a flange 22 integral therewith. At its other end the collar bears against a fitting 23 which is securely keyed to the tube and held against axial movement by nut 32. The collar is free to rotate around the outer tube and is formed with a lever 24 to which is connected one end of a link 26, the other end of which is connected to a lever 25 of an actuator 28 for imparting rotation to the collar. A second collar 29 is fixed to the inner tube [6. A scissors lever 30 connects the rotatable collar 20 with the collar 28 which is fixed to the'inner tube 16, to thereby permit axial movement of the tubes with respect to each other and to provide for rotation of the inner tube through rotation of the collar 28. The fitting 2?. supports the actuator 28' through a bracket 34. A clamp-36 is secured to the outer tube l8 and supports the actuator through a bracket 38.

As best shown in Figures 2 and 3, the actuator 28 is of unitary construction and comprises a hyraulic motor 48 drivably connected to a sector 42 splined or otherwise securely fastened to shaft 44. The shaft is splined on one end at 45 to receive one end of the link 26, and is rotatably supported in roller bearings 46 disposed in each end of a cylinder 48. The bearings are pressed into supporting rings 49 which are held in position in the ends of the cylinder by screws 58 which threadedly engage the rings.

The hydraulic motor includes a cylinder 52 having its axis at, right angles to the axis of cylinder 48. These cylinders may be made from steel tubing processed to the proper size. The walls of the cylinders 48 and 52 have openings 54 and 56 respectively, therein, which are in registry when the cylinders are in assembled relationship. Cylinder 48 is so mounted that its axis is substantially parallel to the axes of tubes l5 and i8 and the axis of cylinder 52 is substantially at right angles to the axes of the tubes. The opening 54 receives the sector 42 which engages a rack 58 disposed in the motor cylinder 52 and carried by piston 50 having ends 62 secured to the rack by studs 64 and provided with sealing rings 86. The reaction on the piston from the load on the gear sector is transferred through the rack 58 to a bearing member 10 interposed between the piston ends and keyed to the rack by pins 12. As best seen in Figure 3 the bearing is configured to conform with the interior of the cylinder 52 to thereby provide adequate bearing surface to minimize the unit bearing load. The bearing fit is controlled by inserting shims 16 between the racl; and the bearing. This also controls the backlash between the gears of the sector and the rack. End members 18 are in-' teriorly threaded at 80 to engage threaded portions 82 of the cylinder 52 to form end chambers 84, 86 in the hydraulic motor 40 into which fiuid under pressure is admitted through ports 88 of the end members.

The admission of fiuid under pressure to one of the chambers and. simultaneously exhausting fluid from the other chambers moves piston and in so doing imparts rotative motion to shaft 44 through the sector 42. Rotation of the shaft 3 44 rotates the collar 20 through the crank arm 26 to thereby rotate the inner tube l8 about its axis to change the direction of wheel 12 to accomplish the desired steering.

Although this invention has been described in 5 connection with certain specific embodiments, the principles are susceptible of numerous other applications that will readily 00.01112? to; persons; skilled in the 'art. The-=invention is; therefore,

to be limited only as indicated by the scope of 10 the appended claims.

Having thus described the variousa-featuressofl the invention, what I claim as new andode'sire to secure by Letters Patent is:

1. An actuator adapted to be mounted om ae 1.55"

landing gear for imparting direction to a wheel thereof comprising a pair of cylindersveach harin g an opening in the wall thereof and arranged in assembled relationship so that their axesareat right angles and the openings are in registry, 20

a shaft-rotatably disposedzin-one of ,thes'cylindersa and adapted. to; be connectedtm thes-wheelz to: guide; the same, in: a predeterminemdireetlon, an gear sector's mounted, on the shaftgfor rotation;

therewith and, having a.- portion: extending n;

throughsaid: openings into; the ;other:cyl1inder, a; c piston; in; said zothencylinder having, a raekthereg on. in driving enga ement; withrsaid geanzsectmt, a bearing memberbarriedz-by theflpistongandmxa tending; longitudinally-,5- thereofi: .foreyslidinggcongs 3Q;

tact with: saidbther ylinder tetherebvtmns-ien reaction, fromthe; piston into ithB: cylinder; :and means interposedbetweenzsaidbearin -ianctpiston:: for; controlling the; backlash, betweenz-ntherrackr andgear sector.

2; A mechamsm: for translating, reciprocal; motion into rotative'motion;comprisinga unitary; structure havinggjaipair of:tubes withztheir sides contiguousand their axes:at::;right;angles, said tubes prcvidedzwith-openings in their sides ar=- i ranged forzalignment, ashaftirotatably positionedi in one of the tubes, 2. gear sector carried by the shaft and having a portion extending through said openings into the other tube, a piston in said other tube having a rack thereon in driving engagement with said gear sector, and an adjustable bearing member carried by the piston and interposed therebetween and said other cylinder for reeeivingthe reaction'ofthegear sector.

3:An actuator adapted to-be mounted on a landing gear for imparting direction to a wheel thereof comprising a pair of cylinders each having,.an opfiningeinthe wall thereof and arranged in assembled relationship so that their axes are atri'ghtz'angles and the openings are in registry, at shaft rotatably'"disposed in one of the cylinders and adapted to be connected to the wheel for guiding,,thesarne,a.v gear sector fixedly mounted on the shaft and having a portion extending throughsthe openings into the other cylinder, 8, piston in said other cylinder having a rack thereon-1 in, driving= engagement with, said gear seoton; a bearing for thQzPiStOIl; constructed-and arranged, to, slide therewith, andadiustably mounted thereon, andshims interposedtbetween saidpistonand bearing for, positioning the bearing -relative,tosaid rackto adjust for backlash between said gear sectorand rack,

STANLEY I; ,MACDUFF.

REFERENCES CITED,

Tire -following references are of record in the file of this patent:

UNITED STATES, PATENTS 35,.5Nt1mber N a'me- Date 669,235 Gardner Mar. 5, 1901 719,562 Brush- Feb. 3, 1903 815,266 Cooper Mar. 13, 1906' 2,0862814-- McCollum July l3, 1937 2;3?2,710= Chisholm Apr; 3, 1945 

